There are many applications in which a laser must be steered in an accurate and controllable way or manner. This controlled steering of lasers has applications in 3D object scanning, LIDAR, and other methods of capturing the distance and the shape of objects. In other applications, there is a need to accurately deflect a laser beam for materials processing, laser printing, medical applications, as well as a number of other applications.
Steering a laser typically requires steering mirrors, lenses, or rotating Risley prism pairs; these methods tend to be expensive and require large amounts of volume and/or weight. Currently, there are many methods for steering a. beam or a laser (e.g., an optical boresight), but all suffer from the associated weight, volume, and/or cost issues. For example, one conventional method of adjusting a laser's direction uses rotating nesting optics, as seen, for example, in FIGS. 1A and 1B. These nesting optics provide a very accurate way to make direct azimuth and elevation adjustments, for example, but they are quite large and heavy and suffer from vibrational interference. In addition, an index matching fluid 2 is present between the optics to facilitate smooth movement.
Another example of current laser steering technology is a Risley prism pair, as seen, for example, in FIGS. 1C and 1D. These prism pairs are typically aligned in the factory, but are often difficult to scan in the field since they do not use orthogonal movement, but rather polar coordinates. Scanning about the optical centerline regenerates singularities in the scan pattern typically requiring a third wedge to simplify the scanner motion.
Risley prism pairs consist of two angled wedge prisms that are rotatable with respect to each other essentially along the axis of the beam. Both wedges require independent adjustment to provide the full range of angles of divergence available for the system. Rotating one wedge in relation to the other will change the direction of the beam. When the wedges' angles are oriented in the same direction, the angle of the refracted beam becomes greater, as shown in FIG. 1D. When the wedges are rotated to orient the two wedged angles in opposite directions (e.g., the thick edge of a first prism faces in one direction and the thick edge of a second prism faces in the other opposite direction to form a parallelogram), the prisms cancel each other out, and the beam is allowed to pass straight through the Risley prism pair, as shown in FIG. 1C. Risley prism pairs provide indirect azimuth and elevation adjustments and use polar coordinates. They can be particularly difficult to adjust for slightly off center.
Yet another current method of beam steering uses radial displacement with lenses (See, for example, FIG. 1E). This method uses traditional azimuth and elevation adjustment, and is used with larger optics. Lastly, pairs of mirrors have been used, as seen, for example, in FIG. 1F. The two mirrors are typically placed orthogonal to each other and they are spaced apart. This system requires large volumes within a device.
In contrast to the existing methods, it is desirable to have an improved system and method which utilizes minimal space and is both lightweight and inexpensive. In addition, the improved system and method will dynamically form an optical wedge with a variable prism having the correct angular offset and direction for the beam deflection.